1. Field of Invention
The present invention relates to an interpolator, and more particularly to an interpolation circuit having a high speed, a high linearity and a high bandwidth, and an interpolation system thereof.
2. Description of Related Arts
High-linearity interpolators are widely adopted in data receiving and transmitting systems, e.g., in function modules such as data sampling module and frequency jitter generating module. Under different digit layout word, a linear interpolator is capable of generating uniform multi-phase clocks. A high-performance data receiving and transmitting system requires the clocks to have extremely high linearity and uniformity.
As shown in FIG. 1, working principles of an interpolator are as following. By inputting Ain and Bin, source synchronous clocks are respectively obtained after different delays. The source synchronous clocks have a phase difference of Φ, which shows up as a time delay tDelay. The interpolator has a phase rotator control word input: PH<0: X>. The control word input controls phase mass of a signal output by an interpolation unit, wherein XεN[1, +∞). During the process that the phase rotator control word PH<0: X> changes from a minimum value (0, . . . , 0) to a maximum value (1, . . . , 1), an output of the interpolator uniformly changes from a front phase Ain to a rear phase Bin, wherein the step size of changing is Φ/2(X+1).
In conventional interpolation circuits, due to limitations of the circuit structure, and especially the constantly improving of the circuit speed (the operating speed>1G), the bandwidth of conventional circuit structures, the linearity and the output swing of interpolators, all decrease greatly. Thus, it is necessary to provide an interpolation circuit having a high speed, a high linearity and a high bandwidth, and an interpolation system thereof.